Nanoparticles synthesized in block copolymer micelles, star architectures, and polyelectrolyte complexes: Characterization and potential under microgravity environments

In this work, we describe the synthesis and characterization of gold nanoparticles from tetrachloroauric acid (HAuCl₄) in block copolymer micelles and star graft block copolymers. In order to achieve complete control of the nanoparticles' properties, as required for several important applications, it is necessary to obtain samples that are as close to monodisperse as possible. Block copolymers offer some advantages compared to low molecular weight surfactants with respect to stability of the self-organized structures, as well as in film formation. In this study, we synthesized a number of poly(styrene)-co-poly(2-vinylpyridine) (PS-C0-P2VP) copolymer architectures such as diblocks and star-block copolymers and investigated the preparation of monodisperse gold nanoparticles using them as nanoreactors. We also report the preparation of gold nanoparticles in aqueous solutions using a polyelectrolyte that possesses pendant reducing oligothiophene groups. Polyelectrolyte complex (PEC) with water-soluble terthiophene derivative was used for the reduction of HAuCl₄ to gold nanoparticles. A number of parameters including solution concentration, percentage of complexation, solvent, reaction time, etc. were investigated. These earthbound studies are necessary to investigate the viability of nanoparticle synthesis under microgravity conditions in space.